Spherical four-bar motion generation and axode generation in cam mechanism design

This work is an extension of the authors' work where RRSS motion generation and RRSS axode generation were used to produce a spatial cam mechanism (D'Alessio et. al., 2013). Here, a cam system design method is presented where spherical four-bar motion generation and axode generation methods are applied. The primary advantage of the spherical four bar linkage, compared to the RRSS linkage, is that the former can be scaled without adding error to the positions achieved by its coupler link. As an example, a concept prosthetic knee is developed to precisely achieve a group of prescribed femur positions.